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Proceedings Paper

Dry etching and surface passivation techniques for type-II InAs/GaSb superlattice infrared detectors
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Paper Abstract

Two of the key challenges in the realisation of focal plane arrays based on type-II InAs/GaSb superlattices (T2SL) are the difficulty in achieving a good sidewall profile and the increased dominance of surface leakage current as the device dimensions shrink. We report the electrical and morphological results of test pixels for mid-wave infrared T2SL photodiodes etched using a Cl2/Ar based inductively coupled plasma reactive ion etching (ICP-RIE) process and passivated using SU-8 epoxy photoresist. The etch rate and sidewall surface morphology of GaSb, InAs, and InAs/GaSb T2SL materials are compared after dry etching under the same conditions, leading to the determination of an optimal etch rate. The effect of surface treatment using selected wet chemical etchants before passivation on the surface leakage current is presented. Limitations of the dry etching recipe and further improvement of the sidewall verticality and smoothness are also discussed. Good sidewall profiles and bulk-limited dark currents are demonstrated for T2SL photodiodes etched to depths between 1.5 and 3.5 μm with a pitch size down to 12 μm.

Paper Details

Date Published: 13 October 2010
PDF: 8 pages
Proc. SPIE 7838, Optics and Photonics for Counterterrorism and Crime Fighting VI and Optical Materials in Defence Systems Technology VII, 783814 (13 October 2010); doi: 10.1117/12.864787
Show Author Affiliations
Siew Li Tan, The Univ. of Sheffield (United Kingdom)
Yu Ling Goh, The Univ. of Sheffield (United Kingdom)
Sankha dip Das, The Univ. of Sheffield (United Kingdom)
Shiyong Zhang, The Univ. of Sheffield (United Kingdom)
Chee Hing Tan, The Univ. of Sheffield (United Kingdom)
John P. R. David, The Univ. of Sheffield (United Kingdom)
Nutan Gautam, The Univ. of New Mexico (United States)
Hasul Kim, The Univ. of New Mexico (United States)
Elena Plis, The Univ. of New Mexico (United States)
Sanjay Krishna, The Univ. of New Mexico (United States)


Published in SPIE Proceedings Vol. 7838:
Optics and Photonics for Counterterrorism and Crime Fighting VI and Optical Materials in Defence Systems Technology VII
Colin Lewis; Roberto Zamboni; François Kajzar; Doug Burgess; Emily M. Heckman, Editor(s)

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